This invention relates to motor vehicle noise insulation and is concerned with a noise insulating partition for dividing the engine compartment from the passenger compartment.
A dividing partition of the above type is, apart from other things, exposed frontally to the noise coming from the engine of the motor vehicle and therefore requires acoustic treatment to achieve the desired noise comfort in the passenger compartment. For this purpose it is known to provide such a partition by providing the wall between the engine and passenger compartments with a covering of noise-insulating material on the passenger compartment side. These noise-insulating materials are ones which require a considerable material thickness in order to obtain the noise comfort desired in modern motor vehicles. It has also been known to apply noise-insulating material in the form of an insulation part on the engine compartment side of the wall.
Such known constructions are disadvantageous in two respects. On the one hand the covering for the passenger compartment side of the front wall can only be assembled under complicated conditions so increased production costs are thus involved. Also, it should be borne in mind that the assembly difficulties increase in proportion to an increase in the thickness of the covering. On the other hand, because of the considerable thickness of covering needed for present-day noise comfort, such known constructions lead to a reduction in the size of the passenger compartment which contradicts existing requirements, viz. to create a passenger compartment with as large a volume as possible. Therefore, there is a demand for "slenderised", i.e. comparatively thin coverings.
In Dr. A. Stankiewicz-Information sheet No. 61 "Efficient noise damping in the modern truck drivers cab", on page 5, column 2 there is described and shown a covering for the engine compartment side of the dividing wall of a forward control type (cab over engine) drivers cab for a truck. The wall here is the bottom wall of the forward control type drivers cab. The covering is applied in the form of a noise-insulating material which is used at the same time as underfloor protection.
With this known construction in the main only slight air noise insulation is effected by the application of the insulating material to the engine compartment side so there is still a need to have a covering on the passenger compartment side. Therefore the aforementioned disadvantages are not eliminated.
Common to both the above-described known solutions is the fact that essentially the noise is only counteracted by the mass of the noise-insulating material. Special measures for reducing the amount of material used are not provided.